Which of the following can cause reflex tachycardia?

Reflex tachycardia occurs as a compensatory mechanism in response to a decrease in blood pressure or an increase in vascular resistance, leading to the stimulation of the heart rate through baroreceptor reflex pathways. An alpha-1 agonist causes vasoconstriction by binding to alpha-1 adrenergic receptors on vascular smooth muscle, resulting in increased vascular resistance and, potentially, elevated blood pressure. When blood pressure increases, the baroreceptors detect this change and respond by triggering a reflex response that increases heart rate to help restore homeostasis, resulting in reflex tachycardia.

In contrast, a beta-2 agonist primarily induces vasodilation and bronchodilation through its action on smooth muscle, which usually leads to a decrease in vascular resistance and has minimal direct effect on heart rate. A beta-1 antagonist decreases heart rate and contractility by blocking beta-1 receptors in the heart, so it does not cause reflex tachycardia. Lastly, an alpha-2 agonist generally inhibits sympathetic outflow and decreases norepinephrine release, leading to reduced heart rate and blood pressure, which would not promote reflex tachycardia. Thus, the activity of an alpha-1 agonist directly links to the physiological mechanism